Golfers and other sports enthusiasts are constantly looking for ways to improve their game. Golfers in particular are relying more heavily on technological innovations to enhance whatever natural abilities they have. Such innovations take the form of improved golf equipment such as golf clubs, golf shoes, golf gloves, golf balls, and even golf attire.
Golfers and golf club equipment manufacturers have been increasingly relying upon sensors and monitors to evaluate a golfer's swing. Sensors and monitors may track conditions, such as club head speed, attack angle, launch angle, golf ball spin rate and spin direction, and so on. And sellers of golf club equipment, including outlets that specialize in golf club fitting, increasingly rely on such sensors and monitors to assist a prospective purchaser in selecting golf clubs that best match their particular golf swing characteristics.
One such sensor that is commercially available is the SB2 sensor available from Swingbyte, LLC (previously Swingbyte, Inc.) of Chicago, Ill. Such sensors, as described in U.S. Pat. No. 8,696,482, incorporated in its entirety by reference herein, are typically removeably attached to the shaft of a golf club, for example with a clamping mechanism, or fixed to the shaft, for example, with an adhesive. Such sensors, also termed “three-dimensional golf swing analyzers,” work as an Inertial Measurement Unit (IMU), and typically include, for example, a three-axis accelerometer capable of producing and transmitting linear acceleration data, a three-axis gyroscope capable of producing and transmitting angular velocity data, a first microprocessor that receives data from the accelerometer and the gyroscope and processes the data, a first computer memory wherein the microprocessor stores the processed data, and a radio transmitter for transmitting the processed data from the first computer memory. MEMS (microelectromechanical systems) technology may be used for the accelerometer and the gyroscope. The sensor is typically powered by a battery or other suitable power source. A housing is used to hold the microprocessor, accelerometer, gyroscope computer memory, radio transmitter, and battery.
Such devices capture and analyze golf swing (or other sporting apparatus motion) data by attaching a sensor to a golf club either below the grip or on the cap, or by integrating the sensor into the shaft. After hitting a shot or swinging the golf club (or other sporting apparatus) players and instructors can view an interactive, three-dimensional animation of the swing, along with key metrics, such as club head speed, path, plane, and various angles at impact. It is generally preferred to affix such sensors at a position remote from the golf club head, due to the head's tendency to vibrate violently at the point of impact, potentially disrupting the sensor's attempts to measure the swing characteristics. Such sensors use a transmitter to send processed linear and angular movement data that defines a sporting apparatus swing, i.e., a golf club swing, to a receiver on a mobile device, such as a smart phone, tablet computer, or laptop computer. A computer application running on the mobile device receives the processed data, processes the data further and displays a graphical representation of the entire swing with comprehensive statistics for every point of the swing. The processed data is stored and later used along with theoretical data to coach a golfer or other sporting apparatus user on his or her swing.
But attaching such sensors, whether to the shaft of a golf club or otherwise, can alter the golfer's normal swing and feel due to the weight of the sensor, which may be 10-50 grams and more commonly around 30 grams. For a 300 gram driver, for example, a 30 gram sensor thus represents a 10% deviation from the club's playing weight. Such added weight may be particularly noticeable to better players, and in particular tour professionals. Moreover, attaching such sensors to the shaft may not be the ideal location for at least three reasons: first, the sensor may be visible/distracting to the player when positioned on the shaft, second, the sensor may be positioned at inconsistent positions along the shaft from club to club or player to player, and third, positioning on the shaft may not be the most beneficial position from which to monitor the user's swing pattern.
Specific to this third point, attaching a sensor to the golf club shaft, for example near the grip, may not precisely monitor the path of the golf club, because during the swing, the shaft flexes, and at impact, the golf club head slows slightly, while the math governing the swing visualization assumes the shaft is substantially rigid and not flexing, so no accelerations to directions other than where the hands seem to be guiding a completely rigid shaft are accounted for. The projected swing path thus follows where the hands would project a rigid cylinder during a swing.
U.S. Patent Application Publication No. US 2013/0267338 A1, incorporated in its entirety by reference herein, discloses a monitoring device including a sensor and transmitter, which may be attached to a golf club head and may be configured to transmit data related to the characteristics of a golf swing to a remote computer.
A problem, however, with mounting sensors in the golf club head is that off center hits (heel or toe, high face/low face), tend to cause the head to wobble back and forth, from the point of impact through a portion of the follow through, for example about half way through the follow through (when the club passes waist height). The accelerometer/gyroscopes/IMUs pick up such club head wobble, and depending on the math driving the algorithm, these forces/accelerations in unusual directions (depending on where the sensor is located) may adversely affect the projected swing path visualization. Moreover, there will be more twisting forces at takeaway (as the shaft torques and hands are rotated). There will be potentially unreliable data at the top of the swing from transition from backswing to downswing (where the shaft flexes quite a bit). With this flex, the orientation of the head to the original (static) might be off 5-10 degrees and twisted 2-5 degrees. At impact, again, the flex and wobble may tend to cause some accelerations. Back and forth oscillation and also at impact, the shaft usually flexes so that the head is flung in front of the static shaft plane and oriented inside the plane (closer to the feet) as the dynamic movement causes the center of gravity of the head to align with the center of gravity of the club.